1. Field of the Invention
The present invention relates to an engine exhaust apparatus for a water-jet propulsion boat in which a water-jet pump casing is provided within a hull, and an impeller in the pump casing is secured to an impeller shaft, which is in turn connected to an engine output shaft in interlocking relation to the output shaft.
2. Description of the Prior Art
A conventional engine exhaust apparatus for a water-jet propulsion boat has until now been arranged such that an exhaust pipe itself, which is connected to an exhaust port of an engine, it extended such as to open into the water or air. In the exhaust apparatus of the type described above, as the length of the exhaust pipe increases, a correspondingly wide space for disposing the exhaust pipe is required.
Further, in the case where the exhaust gas is discharged into the air, the exhaust noise creates a problem. In the case of discharging the extent gas into the water also, various problems arise if the exhaust pipe opens at an undesirable position. For instance, if the exhaust pipe opens forwardly of the impeller, cavitation is unfavorably caused at the impeller portion by the undesirable suction of the exhaust gas. Even at a position rearward of the impeller, if the exhaust pipe opens downwardly of the pump casing, the back pressure in relation to the exhaust gas is inconveniently increased.